• Journal of Positioning, Navigation, and Timing
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• v.13 no.2
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• pp.117-129
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• 2024

In this paper, we survey recent trends of International Global Navigation Satellite System (GNSS) organizations such as the International Committee on GNSS (ICG), International Civil Aviation Organization (ICAO), International Maritime Organization (IMO), and International Telecommunication Union (ITU), and investigate their impact on the maritime and aviation sectors. Each international organization promotes international cooperation, improvement of service quality, assurance of security, compliance with international regulations, and technological innovation and development. ICG develops a variety of satellite navigation enhancement systems. ICAO establishes international aviation regulations and standards to enhance aviation safety and security. IMO establishes international shipping conventions and rules to protect and regulate the shipping environment. Lastly, ITU establishes international communication regulations and standards. Investigation of such international organizations plays an important role in increasing the efficiency and reliability of GNSS systems. Each international organization promotes international cooperation, improvement of service quality, assurance of security, compliance with international regulations, and technological innovation and development. In the future, interoperability and compatibility with new satellite navigation systems and other GNSS and satellite navigation enhancement systems must be secured, so and thus investigation of international organizations must be conducted first.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.8-14
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• 2013

As GNSS(Global Navigation Satellite System) is used in various filed, many countries establish GNSS system independently. But GNSS system has the limitation of accuracy and stability in stand-alone mode, because this system has error elements which are ionospheric delay, tropospheric delay, orbit ephemeris error, satellite clock error, and etc. For overcome of accuracy limitation, the DGPS(Differential GPS) and RTK(Real-Time Kinematic) systems are proposed. These systems perform relative positioning using the reference and user receivers. ETRI(Electronics and Telecommunications Research Institute) is developing precision navigation system in point of extension of GNSS usage. The precision navigation system is for providing the precision navigation solution to common users. If this technology is developed, GNSS system can be used in the fields which require precision positioning and control. In this paper, we introduce the precision navigation system and perform design and algorithm verification.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.1
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• pp.55-62
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• 2006

Ionospheric signal delay is a critical factor for precision differential GNSS(Global Navigation Satellite Systems) applications such as GBAS(Ground-Based Augmentation System) and SBAS (Satellite-Based Augmentation System). Most concern is the impact of the ionospheric storm caused by the interaction between Solar and geomagnetic activities. After brief description of the ionosphere and ionospheric storm, ionospheric models for SBAS are discussed. History of recent ionospheric storms is reviewed and their impact on GNSS is discussed. In order to support Korean GNSS augmentation system development, a preliminary study on the regional ionosphere performed. A software tool for computing regional ionospheric maps is being developed, and initial results during a recent storm period is analyzed.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.1
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• pp.11-17
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• 2007

One of the key elements for developing GNSS (Global Navigation Satellite Systems) is the comprehensive analysis of GNSS satellite orbit including the capabilities to generate precision navigation message. The orbit characteristics of Japan's own GNSS system, called QZSS (Quasi Zenith Satellite System) is analyzed and its navigation message, which includes orbit elements and correction terms, is investigated. QZSS-type orbit simulations were performed using a precision orbit integrator in order to analyze the effect of perturbation forces, e.g. gravity, Moon, Sun, etc., on the orbit variation. A preliminary algorithm for creating orbit element corrections was developed and its accuracy is evaluated with the simulation data.

• Journal of IKEEE
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• v.24 no.2
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• pp.461-467
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• 2020

Most civilian positioning systems in use are based on the Global Navigation Satellite System (GNSS), which receives signals from satellites and calculates the current location. After the successful establishment of GPS from the U.S., GNSS has led to promote satellite navigation systems in various countries. Recently, China has succeeded in the radical development of its own GNSS, the BeiDou Navigation Satellite System (BDS), based on its advanced IT technology and funding power. Considering that China is rapidly expanding the service area of BDS to the world, systematic research on BDS is also required in Korea. Therefore, this paper provides overall information on B1C, the open signal of BDS, so that this information can be utilized in the design of B1C signal system and BDS B1C receiver design.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.1
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• pp.35-44
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• 2024

This investigation primarily focuses on the generational characteristics of satellites utilized in the existing Global Navigation Satellite System (GNSS) and Regional Navigation Satellite System (RNSS), with a central emphasis on comparing the operational status of the latest generation satellites. Variations among satellite generations in physical attributes, energy consumption, and timekeeping are observed, enabling an exploration of the developmental trends over successive generations. Through a comparative analysis of the latest generation satellites, particularly in terms of performance, this study aims to furnish essential insights into the satellites employed within each system. Consequently, it will contribute to a foundational understanding of the past, present, and future GNSS satellites.

• Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.19-22
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• 2010

The accuracy and integrity of global navigation satellite systems (GNSS) can be improved by using GNSS augmentation systems. Large ionospheric spatial gradient, during ionosphere storm, is a major threat for using GNSS augmentation systems by increasing the spatial decorrelation between a reference system and users. Ionosphere decorrelation behavior can be analyzed by using dual frequency GPS data. GNSS receivers have their own biases, called inter-frequency bias (IFB) between dual(P1 and P2) frequencies and they must be accurately estimated before computing ionosphere delays. GPS network data in Korea is used to compute each receiver's IFB, and their estimation accuracy and variability are analyzed. IFB estimation methodology to apply for ionosphere gradient analysis is discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6C
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• pp.512-519
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• 2012

To design a new Navigation Satellite System signal, we should analyze the influence of inter-system interference to existing Global Navigation Satellite Systems(GNSS). Various GNSS systems such as GSP, GALILEO, Compass use same frequence band and incur inter-system interference due to the overlapping spectrums. In this paper, we consider L2 Band for new Navigation Satellite System and propose the BOCcos(15,2.5) signal what has least Spectral Separation Coefficient with GPS L2 system. Assuming 4 stationary satellite over Korea, we simulate the effect of interference. As a result, proposed system shows very small mutual interference effect and negligible effective signal to noise ratio(SNR) loss, compared to the interferences between GNSS systems in L1 Band.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.2
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• pp.113-119
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• 2023

Satellite navigation systems, with the exception of the GLObal NAvigation Satellite System (GLONASS), adopt ionosphere models and provide ionospheric coefficients to single-frequency users via navigation messages to correct ionospheric delay, the main source of positioning errors. A Global Navigation Satellite System (GNSS) mostly has its own ionospheric models: the Klobuchar model for Global Positioning System (GPS), the NeQuick-G model for Galileo, and the BeiDou Global Ionospheric delay correction Model (BDGIM) for BeiDou satellite navigation System (BDS)-3. On the other hand, a Regional Navigation Satellite System (RNSS) such as the Quasi-Zenith Satellite System (QZSS) and BDS-2 uses the Klobuchar Model rather than developing a new model. QZSS provides its own coefficients that are customized for its service area while BDS-2 slightly modifies the Klobuchar model to improve accuracy in the Asia-Pacific region. In addition, BDS broadcasts multiple ionospheric parameters depending on the satellites, unlike other systems. In this paper, we analyzed the different ionospheric models of GPS, QZSS, and BDS in Korea. The ionospheric models of QZSS and BDS-2, which are based in Asia, reduced error by at least 25.6% compared to GPS. However, QZSS was less accurate than GPS during geomagnetic storms or at low latitude. The accuracy of the models according to the BDS satellite orbit was also analyzed. The BDS-2 ionospheric model showed an error reduction of more than 5.9% when using GEO coefficients, while in BDS-3, the difference between satellites was within 0.01 m.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.3
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• pp.16-21
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• 2012

Global navigation satellite systems (GNSS) use dual frequency signals to remove ionosphere delay effect. GNSS receivers have their own biases, called inter-frequency bias (IFB) between dual frequencies due to differential signal delays in receiving each frequency codes. The IFB degrades pseudo-range and ionosphere delay accuracies, and they must be accurately estimated. Simultaneous estimation of ionosphere map and IFB is applied in order to analyze the IFB estimation accuracy and variability. GPS network data in Korea is used to compute each receiver's IFB. Accuracy changes due to ionosphere model changes is analyzed and the effect of external GNSS satellite IFB on the receiver IFB is analyzed.